Oscillator control



Nov. 2, 1937. w LORD OSCILLATOR CONTROL Filed March 16, 1936 Fig.1.

Fig.2.

Inventor:

MM ttorney.

Haw-old \N. Lord, by

His

Patented Nov. 2, 1937 UNITED STATES PATIENT OF FlCE Electric Coll New York m. a corporation of App cation mm is, ms, Serial No. 69,243

' 1: Claims. (Cl. 111-91) My invention relates to electric valve circuits. and more particularly to electric circuits employing electronicdlscharge devices of the gaseous type for controlling electric valve oscillators.

Heretofore there have been devised various arrangements for controlling electric valve oscillators. Many of the prior art arrangements for,

controlling electric valve oscillators have employed electromagnetic devices, electric valves of the high vacuum type or electromagnetic devices controlled by auxiliary electric valves. A distinct disadvantage has been encountered in the use of prior art arrangements for controlling electric valve oscillators. In many of the prior art circuits the auxiliary control apparatus has been subjected to voltages of an order of magnitude substantially equal to the voltage of the main electric valve oscillator. There has been evidenced a decided need for an arrangement whereby electric valve oscillators may be satisfactorily controlled by electronic discharge devices of the gaseous type without employing expensive and complicated auxiliary equipment.

An object of my invention is to provide an improved circuit for controlling an electric valve oscillator which obviates the above mentioned difficulties.

Another object of my invention is to provide a new and improved circuit employing an elec- 30 tronic discharge device of the gaseous type for controling directly an electric valve oscillator.

A further object of my invention is to provide a circuit for periodically controlling an electric valve oscillator by means of a periodic electric timing circuit and an electronic discharge device of the gaseous type.

In accordance with the illustrated embodiments of my invention, I provide an arrangement for directly controlling an electric valve oscillator by 40 means of an electronic discharge device of the gaseous type which is connected across an. im-

pedance element in the oscillator circuit. When the electronic discharge device is conductive so that the impedance element is shunted, the oscillater is started and when the discharge device is rendered non-conductive the oscillator is stopped.

For a better understanding oi my invention, together with other and further objects thereof, reference may be had to the following description taken in connection with the accompanying draw ing. and its scope wil be pointed out in the apperded claims.

In the drawing, Fig. 1 diagrammatically represents anembodiment of my invention for controlling an electric valve oscillator; and Fig. 2

diagrammatically illustrates my invention applied to an arrangement for controlling an electric valve oscillator circuit of the self -rectifying type.

Referring to Fig. 1 of the accompanying drawing, my invention is diagrammatically shown in 6 an arrangement for controlling the energizetion of an electric valve oscillator. An electronic discharge device I of the gaseous type, having an anode 2, a cathode 3 and a control member 4, is provided to control any suitable electric valve os- 10 cillator such as the electric valve oscillator 5. By the use of the term electronic discharge device of the gaseous type, I intend to include electric valves of the gaseous type or electric valves of the vapor type such as those employing mercury 15 vapor. The oscillator 5 as shown comprises an electric valve 3 having an anode I, a cathode I and a control member 9 which cooperates with a parallel connected inductance l0 and a capacitance l2 to generate relatively high frequency 20 electrical oscillations. The inductance III is provided with a tap connection II which serves as a supply connection for the oscillator circuit 5. A self-biasing control circuit for the control member 9 of electric valve 6 includes a capacitance i3 and a resistance II. A current limiting resistance II is connected to the capacitance l3 and resistance ll by a conductor l6; and an impedance element, such as a resistance I1, is con nected in the anode-cathode circuit of electric valve 8. The cathode 8 of electric valve 6 is connected to the anode 2 of the electronic discharge device I through conductors I8, a secondary winding ll of a cathode heating transformer 20 and a conductor 2 I. The cathode 3 of the electronic discharge device i is connected to the resistances It and I1 through a secondary winding 23 of a cathode heating transformer 22, and through conductors 24, 25 and 26. To control the energization of the gaseous discharge device I, I employ a circuit 21 connected across the cathode 3 and the control member 4 through a suitable resistance 28.

The load circuit 29 is energized from the winding 30 which is inductively associated with the inductance l0 and impresses a relatively high frequency potential on the load circuit 29. By controlling the energization of the electronic discharge device I, the oscillator 5 is controlled thereby eflecting control of the circuit 29.

To supply a pulsating unidirectional potential to the oscillator I, I employ any suitable rectifying means such as the electric valve bi-phase rectifier 32 energized from any suitable relatively low frequency alternating current circuit 3|. The rectifier 32 includes electric valves 33 and 34 56 which are energized from the alternating current circuit 511 through a transformer 55 having a secondary winding 55 and which is provided With a mid-tap connection ill. The cathodes of electric valves 55 and 55 are connected through a secondary winding 55 of a cathode heating transformer Elli, and conductors til and it to the tap it of inductance i5, and a conductor 52 is employed to connect the oscillator 5 to the rectifier 52 and serves as the negative side of the direct current source 55, while the conductor 55 serves as the positive side.

Connected across the source of pulsating direct current 55, I employ a capacitance it which serves to lay-pass the high frequency oscillations. To discharge the capacitance M when the oscillator 5 is not operating, a resistance 45 of relatively high value is connected in parallel with the capacitance M and is also connected across the direct current source 55. The lower terminals of the capacitance id and the resistance 55 are connected to the oscillator 5 and the electronic discharge device l by a conductor It.

In explaining the operation of the embodiment of my invention diagrammatically shown in Fig. 1, let it be assumed that the rectifier 32 is supplying a substantially unfiltered unidirectional pulsating potential to the circuit 63. Since the capacitance 54 and resistance 55 are not designed to smooth the pulsating potential of the rectifier, the pulsating output potential of the rectifier 52 will be impressed upon the oscillator 5. If the electronic discharge device i is maintained nonconductive by impressing a suitable negative potential on the control member 4 by means of circuit 2i, the oscillator 5 will not be put into oscillation. However, if the device i is rendered conductive by a suitable potential being impressed on the control member 5 through circuit 211, the device i will be rendered conductive thereby shunting the resistance ill. Upon short circuit- 7 ing the resistance ill through the device l, the bias on the control member 5 of electric valve 5 will be reduced sufliciently to permit the circuit 5 to oscillate to introduce a high frequency modulated potential in the load circuit 29. So long as the device 8 is conductive, the oscillator 5 will oscillate in the manner well understood by those skilled in the art.

The electrical valves 53 and 34 will be rendered conductive alternately to effect rectification of the low frequency alternating current of source 5i to supply a pulsating unidirectional current to circuit Q5. The path of the rectified low frequency current comprises conductor 40, conductor M inductance it, electric valve 5, conductors it, secondary winding it of transformer 20, conductor 2i resistance ll, conductors 26, 46 and 42. When the electronic discharge device i is conductive it, of course, will shunt the resistance l'l causing the rectified low frequency current to flow through secondary winding 23 of transformer 22 and conductors 24, 25, 46 and 42. The circuit for the high frequency electrical oscillations generated by the oscillator circuit 5 comprises inductance lt, capacitance i2, electric valve 5, conductors i8, electric discharge device l, secondary winding 23 of transformer 22, conductors 24, 25 and 45, and capacitance 44.

Near the end of each impulse of unidirectional potential impressed on the oscillator 5 from the alternating current circuit 31! by the rectifier 52, the self-biasing circuit comprising the resistance it and the capacitance i3 causes the circuit 5 to stop oscillation due to the negative bias potenaoeaoei tial impressed on the control member 5 of electric valve 5. The deionization time of the electronic discharge device 9 is not short enough to permit the control member 5 to gain control of the device between cycles of the high frequency oscillations. But the self-biasing action of the capacitance l5 and the resistance it causes the circuit 5 to stop oscillating and interrupts the how of current near the end of each half cycle of alternating potential of source 5i to permit the electronic discharge device i to become non-conductive if a suitable negative potential is impressed on the control member 5 by the circuit N.

If the electronic discharge device 0 is not conductive, the negative bias voltage impressed on the control member 5 of valve 5 will be maintained at this increased value by the subsequent unidirectional impulses, thereby maintaining e ectric valve 5 non-conductive and preventing the circuit 5 from oscillating. This increase in the bias voltage is occasioned by the rectified low frequency current flowing through the resistance ill. When the device i is rendered conductive, the negative bias voltage impressed on the control member 9 of valve 5 is decreased to a value which permits the circuit 5 to oscillate.

Since the oscillator 5 may be controlled by means of the electronic discharge device i of the gaseous type, it should be understood that by controlling the conductivity of the device l through" circuit 21, the energization of the load circuit 29 may also be controlled. During the time the device i is conductive, the oscillator 5 will impress a. train of high frequency electrical impulses on the load circuit 25.

Referring now to Fig. 2 of the accompanying drawing in which a modification of my invention is diagrammatically shown in an arrangement for controlling an oscillator of the selfrectifying type. An electronic discharge device 47 of the gaseous type having an anode 48, a cathode 49 and a control member 50 is employed to control an oscillator 5i of the self-rectifying type, which in turn is employed to energize a load circuit 52.

The oscillator 5| may be energized from any relatively low frequency alternating current circuit 53 through a transformer 54 having a secondary winding 55 provided with a mid-tap connection 56. Electric valves 51 and 58 having anodes 59 and Bi], cathodes 6i and 62 and control members 63 and 64, respectively, are employed in the oscillator circuit 5i to rectify the alternating potential of source 53 and also serve the purpose of generating the high frequency oscillations. A multi-winding high frequency transformer 65 having primary windings B6 and El and secondary windings 6B and 69 is used to impress the voltage appearing across the secondary winding 55 of transformer 54 on anodes 59 and 60 of electric valves 51 and 58, respectively': Transformer 65 also serves the purpose of supplying the necessary inductive reactance for the oscillator 5i. Capacitances I0 and Ill are connected between the upper and lower terminals, respectively, and the midconnection 56 of secondary winding 55 of transformer 56. The anodes 59 and BI] of elec tric valves 51 and 58, respectively, are connected to the secondary winding 55 of transformer 54 through conductors ill and 12, windings 66 and 5'! and conductors l3 and "respectively. A capacitance i5 is connected across the secondary winding 68 of transformer 65 and serves as a part of the high frequency oscillation circuit.

electronic discharge device A self-biasing circuit for energislng the control members 99 and 99 of electric valves 91 and 99 comprises a capacitance 19 and a resistance 11., Current limiting resistances 19 and 19 are connected in series with control members 99 and 99 of electric valves 99 and 91. respectively, and also serve to suppress parasitic oscillations.

To control the oscillator 9i and to render the 91 non-conductive at the end of each half cycle of rectified potentin] of the alternating current circuit 99, I employ a circuit 99 comprising an impedanceelement, such as a resistance 9i, and a resistance 92 and a capacitance 99 connected across the resistance 92; The resistance 9| is connected to the anode 99 of electronic device 91 througha conductor 99, and to the cathode 99 through the parallel circuit ode heating transformer 99. The anode 99 of vapor electric valve 91 is connected to the cathodes 9I and 92 of valves 91. and 99,-respectively, through the secondary winding 99; of a cathode heating transformer 99 and conductors 99 and II. The mid-connection 99 of secondary winding 99 is connected to the left-hand terminals oi" resistances 9i and 92 and capacitance 99 through conductors 92 and 99. Conductor 99 is employed to connect the lower terminal or resistance 11 In the self-biasing circuit to a mid-connection of secondary winding 99 of the high frequency transformer 95.

The timing circuit 99 may beiised tocontrol periodically the conductivity of the electronic discharge device 91 and thereby to effect control of the oscillator By means of the timing circuit 95, a periodic timing potential-of suitable wave form is impressed across the control member 99 and the cathode 99 of valve 91 through a conductor 99 and a conductor 91, conductor 99, resistance 92, conductor 99 and secondary winding 81. The timing circuit 99 is disclosed and claimed in my copending applications Serial No. 585,292 and Serial No. 69,244 filed January '1, 1932, and March 16, 1936, respectively,j.and both of which are assigned to the assignee of the pres ent application. The timing circuit "diagrammatically illustrated in Fig. 2 of the drawing comprises a source of direct current 99, a voltage divider 99 including resistances I99 and Ill, the former having an adjustable contact I92,

a capacitance I 99, a resistance I99, an auxiliary J discharge circuit comprising a serially-connected resistance I95 and a capacitance I 99 and a means for periodically dischargin'g'capacitance I99 such as a vapor electric discharge valve 191 having a control member I99. An inductive'element I99 is connected in series with valve I91 toassis't in the control of the valve I91; and a transformer II9, preferably of the type designed to supply a voltage of peaked wave form, is connected in the control member circuit for electric valve I91 to render the valve I91 conductive precisely at predetermined times. The transformer I I9 may be energized from the alternating current source 93 or other suitable source to control the period of the periodic potential of circuit 99, thereby effecting co-ordination between the control of electronic device 91 and the alternating potential of source 99. A switch II2, having stationary con- I .tacts H9 and H9 connected to the terminals of capacitance I99 and a movable member I", is employed to obtain an adiustment in the ratio of the period of non-conduction to the period of conduction of electronic device 91. When the movable member 9 of switch in is in contact with the stationary member "9, the periodic peaked potential impressed on the control mem ber 99 of device effecting thereby a high ratio of the period of non-conductitm Whereas, when the movable member 9 is connected to cqitact II9 the periodic peaked potential is of longer duration to effect thereby an increase in the period of conduction of device 91 and a decrease in the ratio of the period of nonconduction to the period of conduction.-

The'operation of the embodiment of my invention diagrammatically shown in Fig. 2 may be explained by considering the arrangement when the oscillator 9| is being controlled by the electronic discharge device 91 to supply trains of high frequency oscillations to the load circuit 92. In the manner well understood by those skilled in the art, the electric valves 51 and 99 will operate alternately to rectify the alternating potentiil of the relatively low frequency alternating current source 99 and at the same time will generate relatively high frequency modulated oscillations which are impressed on the load circuit 92 through winding 69 of the high frequency transformer 99. So long as the device 91 is nonconductive the circuit 5i will not oscillate due to the increased negative bias impressed on the control members 99 and 99 of electric valves 91 and 99 through resistance 19 and resistances 11 is due to the rectified low frequency current flowing through the resistance 9i. However, if the dev ce 91 is rendered conductive, thereby shunting the resistance the negative bias voltage on the control members 99 and 99 will be decreased permitting the circuit 9i to oscillate at thefrequency determined by the constants of the circuit.

As explained above in connection with the operation of the embodiment of my invention shown in Fig. 1, near the of rectified alternating potential the self-biasing circuit for the'contr'ol members 99' and 99 of electric valves 51 and 99 will render these valves noncbnductive which in turn will interrupt the flow of current through electronic discharge device 91 for a length of time equal to or greater than the time of deionization for the particular valve used to permit the control member 59 to regain control.

The circuit for the rectified low frequency current supplied from alternating current circuit 99 during a half cycle comprises the upper portion of secondary winding 55 of transformer 99, conductor 1I, primary wind'ng 99 of transformer 99, conductor 19, electric valve 51, conductor '99, secondary winding 99 of transformer 99, conductor 99, resistance 9|, and conductors 99 and 92. During the following half cycle of opposite comprise the lower 99 of transformer 99, conductor 12, primary winding 91.0! transformer 99, conductor 19, electric valve 99', conductor 9i, secondary winding 99 of transformer 99, conductor 99, resistance 9I and conductors 99 and 92. Of course, when the electronic discharge device 91 is conductive permitting circuit II to oscillate, this device will eifectively shunt the resistance 9i to by-pass the low frequency current through the device 91, secondarywinding 91 of transformer 99, conductor 99, and the parallel circuit comprising resistance 92 and capacitance 99. The capacitance end of each half cycle ti will impress a negative potential on the anode it of electronic device it through the resistance iii to efiect deionization of the device and render it non-conductive at the end of each one halt cycle period of conduction oi low frequency current.

Where it is desired to obtain periodic energizetion of the load circuit ht, a periodic control potential may be impressed on the control member ht of electronic device ill by means of the timing circuit $5. The timing circuit will periodically render electronic device till conductive to set the circuit it into oscillation to supply trains of high frequency oscillations to the load circuit it. The periods of energization and the intervals between the periods of energization of the load circuit may be determined by choice of the constants for the timing circuit tit and the setting of the adjustable contact Hit.

By virtue of my invention, as illustrated by the embodiment described above, I provide arrangements for precisely and reliably controlling electric valve oscillators by means of electronic dis charge devices of the gaseous type. I have found that by means of my invention the voltages appearing across the control device are very much less than the control voltages which are involved when the prior art arrangements are used. For example, where the voltage appearing across the secondary winding it of transformer iii in Fig. 2 is approximately 2200 volts, the forward voltage appearing across the control valve ll will be approximately 70 arrangements the control device would be required to handle a voltage of approximately 7'10 volts.

While I have shown and described my invention as applied to a particular system of connections and as embodying various devices diagrammatically shown, it will be obvious to those slnilled in the art that changes and modifications may be made without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is 1. In combination, a source of pulsating unidirectional current, a load circuit, an oscillator circuit comprising an electric valve means interconnecting said source and said load circuit, and means for selectively rendering said oscillator circuit oscillatory and non-oscillatory in accordance with a decrease of said pulsating current to a predetermined minimum value comprising an impedance element connected in said oscillator circuit, an electronic discharge device of the gaseous type connected across said impedance element for rendering said oscillator circuit oscillatory when in a conducting condition and non-oscillatory when in a non-conducting condition and a control circuit for rendering the discharge device conductive.

2. In combination, a source of pulsating unidirectional current, a load circuit, an oscillatorcircuit comprising an electric valve means interconnecting said source and said load circuit and means for selectively rendering said oscillator circuit oscillatory and non-oscillatory in accordance with a decrease of said pulsating current to a predetermined minimum value comprising an impedance element connected in said oscillator circuit for maintaining said circuit non-oscillatory, an electronic discharge device volts, whereas in the prior art a: not

oi the gaseo type connected in parallel with said impedance element for rendering said oscillator circuit oscillatory when in a conducting condition and non-oscillatory when in a nonconducting condition and a control circuit for rendering said electronic discharge device conducting.

3. In combination, a source of pulsating unidirectional potential, a load circuit, an oscillator circuit interconnecting said source and said load circuit comprising an electric valve means having a self-biasing control circuit, and means for selectively rendering said oscillator circuit oscillatory and non-oscillatory in accordance with a decrease of said pulsating potential to a predetermined minimum value comprising an inrpedance element connected in said oscillator circuit for maintaining said circuit non-oscillatory, an. electronic discharge device connected in parallel with said impedance element for rendering said impedance element inefiective at predetermined intervals established by said source and a control circuit for rendering said electronic discharge device conductive.

i. In combination, a source of pulsating unidirectional potential, a load circuit, an oscillator circuit interconnecting said source and said load circuit comprising an electric valve means and a self-biasing control circuit therefor, and meansior selectively rendering said oscillator circuit oscillatory and non-oscillatory in accordance with a decrease of said pulsating potential to a predetermined minimum value comprising an impedance element connected in said oscillator circuit for controlling said self-biasing control circuit for said electric valve means to render said electric valve means non-oscillatory, an electronic discharge device of the gaseous type connected in parallel with said impedance element for rendering said oscillator circuit oscillatory when in a conducting condition and non-oscillatory when in a non-conducting condition and a control circuit for rendering said electronic discharge device conducting.

5. In combination, a source of pulsating unidirectional potential, a load circuit, an oscillator interconnecting said circuits comprising an electric valve means and a self-biasing control circuit for said electric valve means, an impedance element connected in the anode-cathode circuit of said electric valve means, and an electronic discharge device of the gaseous type connected across said impedance element for controlling said oscillator, said self-biasing control circuit being arranged to render said electric valve means non-conductive for a period greater than the time of deionization of said electronic discharge device to permit said electronic discharge device. to control said oscillator near the end of each pulsation of said unidirectional source.

6. In combination, a source of pulsating unidirectional potential, a load circuit, an oscillator circuit interconnecting said circuits comprising an electric valve having a control member and a self-biasing control circuit for said control member and arranged to render said electric valve non-conductive when said pulsating potential decreases to a value less than a predeter mined critical value. impedance means connected in said oscillator circuit to maintain said valve non-conductive, and an electronic discharge device of the gaseous type connected across said means for controlling said oscillator circuit.

a source of pulsating unia load circuit, an oscillator interconnecting said circuits comprising an electric valve having a control member and a selfblasing control circuit for said control member of said electric valve and arranged to render said electric valve non-conductive when said pulsating potential decreases to a value less than a predetermined critical value, an impedance device for maintaining said valve non-conductive, and an electronic discharge device of the gaseous type connected in parallel with said ment for shunting said impedance element to render said impedance element inefl'ective at predetermined intervals.

8. In combination, an alternating current circuit of relatively low frequency, a load circuit, means interconnecting said circuits comprising an electric valve oscillator circuit and a rectifier energized from said alternating current circuit for supplying a pulsating unidirectional current to said oscillator, and means for selectively rendering said oscillator circuit oscillatory and nonoscillatory in accordance with a decrease of said pulsating current to a predetermined minimum value comprising an impedance element connected in said oscillator circuit for controlling said oscillator, an electronic discharge device of the gaseous type connected across said impedance element for rendering said oscillator circuit oscillatory when in a conducting condition and non-oscillatory when in a non-conducting condition.

9. In combination, an alternating current circuit of relatively low frequency, a load circuit, means interconnecting said circuits comprising an electric valve oscillator circuit and a rectifier energized from said alternating current circuit for supplying a pulsating unidirectional current to said oscillator circuit, means comprising an impedance element connected in said oscillator circuit for controlling said oscillator near the end of each-unidirectional electrical impulse impressed upon the oscillator circuit by said rectifier, and an electronic discharge device of the gaseous type connected across said impedance element for rendering said impedance element ineffective at predetermined intervals.

10. In combination, an alternating current supp y circuit, a load'circuit, an electric valve circuit for rectifying each half cycle of the current of said alternating current circuit and for converting the energy thereof into high frequency oscillations, and an electronic discharge device of the gaseous type connected in the anode-cathode circuit of said electric valve circuit for controlling said electric valve circuit.

11. In combination, a source of alternating current, a load circuit, an electric valve circuit interconnecting said circuits for rectifying each half cycle of the current of said alternating current circuit and for converting the energy thereof into high frequency oscillations, an impedance element connected in the anode-cathode circuit of said electric valve circuit for controlling said electric valve circuit, and an electronic discharge device of the gaseous type connected across said impedance element for controlling the effective impedance of said element in said electric valve circuit.

12. In combination, an alternating current supply circuit of relatively low frequency, a load circuit, an electric valve circuit including electric valve means for rectifying each half cycle of the current of said pp y circuit and for converting .7. In combination, directional potential,

- said electric valve impedance ele-' the energy thereof into high frequency oscillations to produce in saidload circuit relatively high frequency electrical oscillations, a self biasing control circuit for said electric valve means for rendering said electric valve means non-conductive at the end of each electrical impulse, and means comprising an electronic device ofthe gaseous type connected in the anode-cathode circuit of said electric valve circuit for controlling circuit.

l3. In combination, an alternating current supply circuit, a load circuit, an oscillator circuit interconnecting said circuits for rectifying each half cycle of the current of said supply circuit and for converting the energy thereof into high frequency oscillations comprising an electric valve means, and means for controlling said electric valve means at the end of each half cycle of current supplied from said alternating current circuit in accordance with a decrease of the rectifled current to a predetermined minimum value comprising an impedance element connected in said oscillator circuit for maintaining said electric valve means non-conductive, an electronic discharge device of the gaseous type connected across said impedance element for rendering said impedance element ineffective at predetermined intervals and a control circuit for rendering said electronic discharge device conductive.

14. In combination, an alternating current supply circuit, a load circuit, an oscillator circuit interconnecting said circuits for rectifying each half cycle of the current of said supp y circuit and for converting the energy thereof into high frequency oscillations comprising electric valve means, an electronic discharge device of the gaseous type connected in said oscillator circuit for controlling said electric valve means, and means connected in the anode-cathode circuit of said electronic discharge device for controlling said electronic discharge device.

15. In combination, an alternating current supply circuit, a load circuit, an oscillator circuit interconnecting said circuits comprising electric valve, means, a self-biasing control circuit for rendering said valve means non-conductive at the end of each half cycle of potential of said alternating current circuit, means connected in said oscillator circuit for maintaining said valve means non-conductive after said valve means has been rendered non-conductive by said control circuit, and an electronic discharge device of the gaseous type for rendering said last-mentioned means ineffective at predetermined intervals.

16. In combination, an alternating current supply circuit, a load circuit, an oscillator circuit interconnecting said circuits for rectifying each half cycle of the current of said supply circuit and for converting the energy thereof into high frequency oscillations comprising electric valve means, a self-biasing control circuit for rendering said valve means non-conductive at the end of each half cycle of potential of said alternating current circuit, an impedance means connected in said oscillator circuit for maintaining said electric valve means non-conductive after said electric valve means has been rendered non-conductive by said self-biasing control circuit, an electronic discharge device of the gaseous type connected across said impedance element for rendering said impedance element ineffective, and means comprising a parallel condischarge device for controlling said electronic rue device. 1'7. In combination, an alternating current supply circuit, an alternating current load circuit, electric translating apparatus for transmitting energy therebetween comprising a full wave rectifier including a pair of unidirectional conducting paths arranged to conduct current alternately, an electronic discharge device, at the type employing an ioniaahle medium and having a control member, connected in circuit with said unidirectional conducting paths for controlling the transfer of energy from said supply circuit to said load circuit, and means connected across said electronic discharge device for rendering said device nonconductive at the end of each half cycle of conduction to permit said control member to obtain control.

18.1n combination, an alternating current supply circuit, an alternating current load circuit, electric translating, apparatus connected therehetvreen comprising an inductive Winding having terminal connections and a connection electrically intermediate said terminal connections, a pair of electric valve means each connected in circuit with a different one oi said ter minal connections and arranged to transmit current alternately, an electronic discharge device 

